An architecture called “IP Multimedia Subsystem” (IMS) has been developed to enable multimedia services and sessions for user terminals connected to different access networks. The signalling protocols “SIP” (Session Initiation Protocol) and RTSP (Real-time Streaming Protocol) can be used for initiating media sessions between different parties, as controlled by specific session control nodes in a so-called “IMS core” controlled by an IMS services operator.
Techniques and protocols are also established for multimedia communication between devices in a limited local network using internal addressing and transport means, also referred to as a residential or office network, LAN (Local Area Network), private or home network. The devices in a local network may include any types of entities capable of communication in the network, such as fixed and wireless telephones, computers, media players, servers and television boxes, the latter also called “STB” (Set Top Box).
The architecture called UPnP (Universal Plug-and-Play) can be used for communication in a local network between different devices that may use different operating systems, programming languages, format standards and communication protocols. Further, DLNA (Digital Living Network Alliance) is a recently developed technology for acquiring, storing and accessing media content from devices in a local network.
In DLNA, different communication schemes have been defined for different scenarios, including the so-called “3-Box” scheme. According to this scenario, which is illustrated in FIG. 1, a first device can be used within a local network 100 for controlling the transfer of media stored on a second device to a third device in the network. Here, a small handheld wireless phone 102 with limited playout capacity is used as a control device to direct either a laptop computer 104 or a media server 106 to stream media content to a TV set 108 in order to play out the content with greater quality as compared to both the handheld device and the laptop computer. The TV set 108 is thus used as a “rendering device”.
The concept of IPTV (Internet Protocol TV) has also become widely popular in recent times, where a user can obtain media from an IPTV provider by means of streaming or downloading over the Internet. It is further possible to request media from an IPTV provider using an IMS subscription as credentials for authorising the user and his/her terminal towards the IPTV provider. A user can also obtain the IPTV service to a mobile terminal using a conventional SIM (Subscriber Identity Module) card or similar in the terminal.
When utilising an IMS subscription, a corresponding ISIM (IMS SIM) is typically required for gaining access to the IPTV service. FIG. 2 illustrates this situation where an ISIM is installed in a laptop computer 200 or other IMS-enabled communication device, which then requests for media via an IMS core 202 from an IPTV provider 204. After the IMS core 202 has authorised the requested media transfer to computer 200, the IPTV provider 204 can allow media to be streamed or downloaded thereto over a public transport network such as the Internet. Thereby, the user is able to consume TV content on the IMS-enabled device 200 according to his/her IMS subscription and utilising a pre-established security relation with the IMS operator and using the ISIM to provide valid credentials.
In addition, it would be desirable to enable a user to play out content on an external visited rendering device, as obtained from an IPTV provider or from any other provider of any content such as TV programs, films, any visual and/or audio content, game related content, and so forth. For example, a user may stay at a hotel or visit a friend and want to obtain and play out media on a TV set at the hotel or friend's home, using his/her IMS subscription. However, this may not be possible unless the user can insert a movable ISIM into the visited device and use it for accessing the IMS core to be authorised to obtain the media from the provider. Obviously, many user devices such as TV sets are not equipped to receive and handle such an ISIM or corresponding movable credentials tool.
Another problem that can be identified when not being able to use valid IMS credentials or similar for obtaining media to a visited rendering device, is that neither the user nor the content provider can have secure control of the media transfer to the rendering device. For example, the content provider may not know if the content is accessed only by an authorised party, and conversely the user cannot be sure the content is delivered in a proper manner.
Another problem generally associated with media deliveries from an external content provider is that the user is not able to stop the media transfer if, for some reason, he/she is not satisfied with or ready for the delivery. For example, the rendered quality may not be up to expected standard, or the content may be received incompletely or not at all. A visited rendering device may further be unable to play out the received media format in a proper manner. The user may even have requested the wrong media content or type of media by mistake, and so forth. On the other hand, the content provider also cannot discover if the requesting user has stopped receiving media, e.g. due to intentional power-down or unintentional loss of connectivity.